The present invention relates to an optical instrument for observing an object with both eyes and in particular to a stereoscope in which at least one or both eye pieces are slidable to a frame.
In the prior art, a binocular magnifying lens constituted either by a combination of two convex lenses or adapted to utilize a prism action of a lens by deflecting an optical axis from the center of the lens has been known.
However, the above structure could not provide a binocular magnifying lens with a high magnification nor for the same reason as the fact that when a person with normal vision uses spectacles for the aged, it is tiring; its use could not be endured for long periods of time.
Further, in a magnifying lens which utilizes a prism action, there is the defect that a long distance between the eyes and the lens (the eye point) is required.
Moreover, in a conventional stereoscope, when it was used in a dissection, after the dissected body resting on the dissecting table was observed with a stereoscope, and because of further need to observe in detail by magnification with a microscope; it was necessary to transfer the dissected body to a sample holder of a microscope.
It is the general object of the invention to provide a stereoscope which can eliminate the above defects of the conventional stereoscope. It is the principal object of the invention to provide a stereoscope in which an optical axis meets an object and high magnification can be obtained by combining the eye pieces with an objective lens, with the center of the objective lens deviating from the optical axis of the eye piece by which a prism action is utilized, thereby reducing eye strain when used for long periods of time.
It is a further object of the invention to provide a stereoscope in which a frame of the stereoscope and a microscope body are replaceably disposed on one base stand whereby observation on one sample holder can be made with the stereoscope for a wide visual range and increased magnification can be provided with the microscope.
According to the invention the stereoscope is composed of a pair of eye pieces and an objective lens, one or both of which are slidable to the frame, fitted into the frame so that the optical axis of the eye pieces deviate from the center of the objective lens.